Caption: Woman undergoing a mammography examination, an X- ray technique used for the early detection of cancerous tumours of the breast. A mammogram is an ordinary, low-dose, X-ray image of the breast that shows fine details of the internal soft tissues. To obtain an image, the breast is compressed into a relatively flat plane between two plastic sheets before exposing the tissue to a narrow range of X- ray wavelengths (typically 30-40 kilovolts). Small tumours detected at an early stage may sometimes be removed without resort to a mastectomy, the surgical removal of the whole breast.